Description: In a k-regular graph, the number of walks of a fixed length n from a
fixed vertex is k to the power of n. This theorem corresponds to
statement 11 in Huneke p. 2: "The total number of walks v(0) v(1) ...
v(n-2) from a fixed vertex v = v(0) is k^(n-2) as G is k-regular." This
theorem even holds for n=0: then the walk consists of only one vertex
v(0), so the number of walks of length n=0 starting with v=v(0) is
1=k^0. (Contributed by Alexander van der Vekens, 24-Aug-2018)(Revised by AV, 7-May-2021)(Proof shortened by AV, 5-Aug-2022)